The present disclosure herein relates to methods of forming a semiconductor device, and more particularly, to methods of forming a semiconductor device having a contact structure.
In general, semiconductor devices include an integrated circuit having specific functions. The integrated circuit is typically fabricated by forming numerous discrete devices in a limited area of a semiconductor substrate. The discrete devices may include active devices such as transistors and passive devices such as resistors and capacitors.
The discrete devices may be formed on the semiconductor substrate or on an insulating layer stacked on the semiconductor substrate. The discrete devices may be electrically connected to each other through conductive contact plugs penetrating the insulating layer and interconnection lines in contact with the contact plugs. In conventional practice the forming of the contact plugs typically includes the forming of contact holes that penetrate the insulating layer and the forming of conductive patterns that fill the contact holes.
However, as semiconductor devices become more and more highly integrated, the aspect ratio of the contact holes, that is, the ratio of the length of the hole to the width of the hole, has been increased. As a consequence, it becomes difficult to completely fill the contact holes with a conductive layer. That is, empty voids may be produced in the contact plugs formed in the contact holes. When the voids are formed in the contact plugs, the voids may sharply increase the contact resistance between the respective contact plugs in the contact holes and the interconnection lines in contact with the contact plugs. Moreover, such voids can degrade the reliability of the semiconductor devices, particularly if such voids create potential gaps/disconnects in the current paths between the contact plugs and the interconnection lines.